Organic photoreceptors provide good performance and have various advantages over inorganic photoreceptors, and therefore organic photoreceptors have been used for image forming apparatus such as copiers, facsimiles, laser printers, and multifunctional products having two or more of copying, facsimileing, printing functions instead of inorganic photoreceptors.
In general, a protective layer is formed on such organic photoreceptors to prevent abrasion of the photoreceptors due to mechanical stresses applied thereto by developing systems and cleaning systems of the image forming apparatus for which the photoreceptors are used.
When such organic photoreceptors are charged by a corona charger in image forming apparatus, the organic photoreceptors cause an uneven density problem in that when the photoreceptors are repeatedly used for a long period of time and are charged by the corona charger after a long pause, a strip-shaped uneven density image having the same width as the width of the corona charger is formed.
An electrophotographic photoreceptor having an electroconductive substrate, a photosensitive layer located on the electroconductive substrate, and a protective layer located on the photosensitive layer is disclosed, wherein the protective layer is formed by applying a coating liquid including a binder resin component including a specific crosslinkable acrylic monomer and a particulate electroconductive metal oxide on the photosensitive layer, and then crosslinking the applied coating liquid.
However, it is difficult for the photoreceptor to have good abrasion resistance while preventing occurrence of an irradiated-portion potential increasing problem in that the potential of irradiated portions of the photoreceptor increases after the photoreceptor is used for a long period of time.
For these reasons, the inventors recognized that there is a need for a photoreceptor which has good abrasion resistance and which does not cause the uneven density problem while preventing occurrence of the irradiated-portion potential increasing problem.